July 17, 2009

Tranquility Base, 40 Years Later

Today NASA released the first photos of the Apollo 11 landing site taken by the Lunar Reconnaissance Orbiter
(LRO), which reached lunar orbit on June 23 and has been gearing up for its
year-long mission to study potential safe landing sites for future lunar
exploration missions. The images were the first post-Apollo-era photos to
clearly resolve hardware on the moon’s surface, according to Mark Robinson, project
leader for the LRO Camera (LROC) at Arizona
State University.
Other Apollo-site images captured by Chinese, Japanese, and Indian satellites
have not been able to clearly show hardware, Robinson said in a teleconference
discussing the images.

Apollo 14, 15, 16, and 17 sites were also imaged, with the Apollo 12 site set to be captured on
camera in the coming weeks. Due to the LRO’s orbit and the sun angle at each
pass, the site images varied in their sharpness. Most came in at a resolution
of around four feet per pixel, with the 12-foot-diameter lunar landers taking
up about nine pixels. Because the images were taken with the sun low on the
horizon, their shadows were clearly visible.

However, the photographs of the Apollo
11 site do not appear to indicate whether the first flag planted on the
moon still stands. According to some sources, astronaut Buzz Aldrin claims he
saw the flag fall as the lunar module’s ascent stage lifted off. Because Aldrin
and Neil Armstrong stayed close to the lander, planting the American flag
within 50 feet and in soft soil, it is highly probable that the flag fell.
Later missions made a concerted effort to plant the flag farther from the lunar
module, and to hammer it into the lunar surface. Astronaut Gene Cernan commented
in the Apollo 17 Lunar Surface Journal,
“I don’t know how deep it went, but deep enough that it was very
firmly planted….Nothing’s going to blow that flag over.”

Robinson said that because of the flag’s small size, it would measure less
than a pixel, and if seen from overhead, it would be very narrow indeed. You’d
have to be “optimistic” to think you could see it, Robinson
suggested. If the flag were lying down, of course, the chances of spotting it
might be better.

The LRO’s cameras went through a few days of testing to make sure they were
in focus before capturing the Apollo site images. Because water got into parts
of the telescope equipment while still on Earth–a routine occurrence, Robinson
says–his team turned off the cameras to turn on special heaters to dry out the
equipment over several days, ensuring that photos would be as sharp as
possible. The LRO carries two high-resolution, narrow-angle cameras and one
lower-resolution, wide-angle camera.

Future Apollo images taken from a different orbit and with different sun
angles should allow the LRO to take pictures with two to three times the
resolution of these early images. Mike Wargo, chief lunar scientist at NASA headquarters
in Washington, DC, emphasized in today’s teleconference that the current images
represent “only a first glimpse … the first of many images to be coming
of the Apollo sites, and from now they’re only going to get better.”